Future example

gistfile1.scala

def fetchUserData(userId: Int): Future[UserData] = {...} // method which returns user data in the future
def loadFromUrl(url: Url): Future[Bitmap] = {...} // method which returns a bitmap in the future
 
val avatar: Future[Bitmap] = 
  for {
    userData <- fetchUserData(1) // bind user data to value 'userData' as soon as it is available 
    avatar <- loadFromUrl(userData.avatarUrl) // use 'userData' from above (when it is available) and then 
                                             // load the bitmap and bind it to 'avatar' as soon as it is available
  } yield avatar // return the avatar bitmap as a result
  
// the value 'avatar' will contain a bitmap as soon as the the chain the for comprehension is executed
// no blocking of threads will happen at any point !